Sheet metal shears with linkage



e 9, 1954 QB. GARLAND SHEET METAL SHEARS WITH LINKAGE Filed Feb. 5, 195

(2.4005 6. kmamvo INVENTOR. BY 2 y 177' TOP/v5 x Patented Feb. 9,1954

SHEARS WITH LINK-AGE olaude L Garland;. q mntom=; la sism one1halif:, to',Carl-Erye, Long Beach, Calif. 1.

Application February-5, 1951'}Serlal-Nos209;335e I 3C1aims.; (Cl. 30.-,-242.),.-- 1. 2- This-invention relates .to a sheetzmetal shears and particularlysa "sheetmetal shears-adapted 1 1 for manual operation. t

In the conventionalhandoperated: sheet metal,

arms rare pivoted to each i-lothertatv .a. i common" transverse fulcrum-axis, which is lusuallylocated substantiallyxnearer one end .of the levers than; the ,:other .;end thereon: The longerrendssof; their; levers arer-v provided with hand grips and the 71 smooth, clean cut Furthermarexthfi cutting {a shorter lends with-cutting.-.edges, which taszl.the;;-l. levers movewaboutz their;v common v iulcrunrgaxiszy 2 movertoward and; away gfrom .eachyother in a cutting-1 plane -perpendicular:. tozthe fiWOrkIL'Sheet; 7.

fulcrum. ;axis outwardly; of, the. ,rlVOrk =1; sheet-1; tin snipse-aretof :the scissors-,;type-;.of;shearing: tool;

i. e the fu1crum;axis1is.ofs.et inwardlylwith-lreec, spect: to the: line of. :the cutting ;-.edge: of at :;-least neof eim vement otl ebladestoward ach alined-r-withq both cutting".edges, .;-these redg eszaz. wouldgvcontactgeachzpther ,1 simultaneously; at gall; l l points, :of their length, ..The;too1-wou1d:1then not; beret thegscissors type; but.;wou1dibelofltherlpliers. andzw u dtr quirethe:applicatiomof n exssite;squeezinspressureto etiechacutnf the workzsheetthezentirellength oithe .cutting edges at Cones-instant; or

As the; application ofthisexcessive-pres ure .18. l. i mpractical.fomhand:,0perated.;.sh ars to sever; it.

If thepblades; of ;a hand operated metal shears early traveling blades are slightly inclined T815,-

powenof :a traveling cut will be realized. sci sqlts- Timsnlnsairscissorsrtyne she rselhaye;in;

movementtowardandaway from each other.

It is another object to provide a hand operated she, eeh etrmust 1 91 :zertically awayf rorn; eaeh.;; severance with. a minimummf bending from the other, being bent and directed away iromfiachi plane of th thernytt e ';me ?l;1. i ihfiibQ iyo thezleve sk'to ea ee .-;o e: cuttin ..3:n11i Q -1Q;th;; bs the liu crumnivot l eonnept o -and; xw ndi is; 511. 3 otor-the hand ,e. line-fi p r, e of theiconstructi n 9i sn -nsor.. ,is er i t i 1 i ficoittaprovide: .throa ito r ive e. sewdls eet port ons rearwardlnofrthmcuttin a edges without bending them excessively as the outthelengthof the cut ioreach. successive po- "sition of theashears along the sheet" metal shears. of compact, construction, reliable. in

vantagebecomesseriousin the-case of.-relative1y; minimum of effont by t athick sheets: of.' metala.which .resist:.this.; bending..,.. lathe -drawings, action-,4.limitingrthelfield. of :use. of v-timsnips It is ialsordimcultto'zprovidetior ;thehandling.;par= enl bpgiying the jnyenpipn; I

tion-, of, the sheet to, thesrear of the cut,.which l .1 tends ;.as, its, length increases to drop wdownwardly of :its; :weiglrtqin .a reverse curve, requiring more manual pressure to .efiect the cut, and makin :it e h ar ipopularly.lmown as .ftin-snipsutworlever 1 more: diflicult;.for, the operator-"to followua;

Tinsnipstendto stretch theme al. at the cut-,1 me p int, .;d ue;to the-,MertiQaI div r ence of the; two severed 1 portions of the sheet preventingsa e egb we n any two piv ed.blades.- ie rea esas;v the.blades-passeach; other; soeeclins up rthea ravr 61 of thep int of severance, ma insit ne es a y t apply;increas n *.m'essur e t :the; handles. as; In .orderto;accomplish-a.travelin ccutf omzthe.. -the cutting angledecreases, Also at thebegintheltiithe cut in z an e s :so iereatzthat zen-1111:. due; component. of t e; za rc a p ied. y the. .01 1: a-toris st zinrush n ith cutt ng, ;.blades lon oneqoi ;,the .levers,--. for if the fulcrumrgaxis;were:;2 -lgitudinallyof the sheet, as compared to the pressure effectively-applied transversely of the sheet are;so mountedas to approach each=-,other for, the cutting operation, I in 1 a relatively rectilinear: manner;v suchas.: characterizes ,-power operated squaremetal shears, the above disadvantages of pivotally imounted blades vwill be obviated. And i if the cutting edges of these relatively rectilin-,-

'tiveto eachlother, the-advantages of the low It is one object of this invention-to provide-a hand. operated metal shears in which the cutting; herent disadv u to the Pivotal .21.117. bladesishallrhave a relative rectilinear cutting:

metalshearsin which the two severed sheetpon tions may-travel rearwardlyiirom the point of.

It isanother object to provide av hand operated metaL-shears in vwhichthe applied power shall berelativelylight and shall, be constantthrough- It is another object to providea hand operated l its ,operation, whichshall make a clean smooth snipsitmvehforwargly ofjhgshegt Thisflisad; cutwithoutdeforming the work sheet, andwith.

Figured isa side elevation of a metal shears,

Figure 3 is a sectional view taken as indicated by the line 33 of Figure 1;

Figure 4 is a sectional view taken along the line 44 of Figure 1.

The shears comprises a lower cutting blade i5, an upper blade 12, handles I3 and It for the blades l and I2, respectively, and the several devices to be presently described for connecting the blades for relative rectilinear movement, and for connecting the handles to the blades.

The blade |5 and handle |3 are rigidly related and are preferably portions of a single forging in the general form of a horizontally disposed yoke open at its leftward end as seen in Figure l, for the reception of the work sheet. The lower leg of the yoke constitutes the lower blade l5 of the shears, having a cutting edge |6. The upper blade |2 has a cutting edge 25 formed preferably on a replaceable inset 25'. The upper leg H of the yoke H is the leftward end portion of the handle |3 and is laterally offset from the blade l5, the left face of the upper leg as seen in Figures 3 and 4 being substantially coincident with the right face of the blade I5. The two legs are connected by a neck |8. The neck and adjoining parts of the yoke are shaped to provide an upwardly facing, generally horizontal surface |B upon which the one portion of the severed sheet rests, and a downwardly facing generally horizontal surface 29 against which the other portion of the severed sheet bears upwardly. The surfaces l9 and are not quite parallel but form an acute angled edge 2i at their forward ends and very gradually diverge rearwardly extending to the rear face of the neck It.

The two portions of the severed sheet move rearwardly over these surfaces and are slightly bent apart at the edge 2|, being separated as they leave the shears by a vertical spacing equal to the depth of the distance between the rear ends of the surfaces |9 and 29. If the work sheet is supported by a work table during the shearing operation, the slight bending of the sheet as it rises to enter the opening between the blades, and the further slight bending of the severed-sheet portions, first at the edge 2|, and later as they drop toward and onto the table as they leave the shears, offers no real difficulties in performing the cutting operation.

The upper leg I? of the yoke overlies the upper blade |2. It has two parallel vertical bores 22 overlying the two end portions of the blade l2, respectively, which slidably receive the two pins 23 and 24. These pins at their lower ends are rigidly secured to the blade l2, as by a pressed fit, a threaded connection or in other suitable fashion. The blade |2 will then of necessity travel in straight lines with respect to blade I5. The blade I2 is mounted on the pins 23 and 2a with its cutting edge 25 at a small acute angle a to the cutting edge lt of the blade I5 so as to effect a traveling cut of the work sheet between them requiring a relatively small thrust force between the blades. The cutting angle a between the blades remains constant from one end of the cut to the other, with the result that the cutting pressure is also constant.

The handle M is connected to the blade l2 by a linkage system arranged to apply thrusts of equal value to the pins 23 and 24 as they are held to their parallel travel transversely of the leg H. The handle M is forked at 26, the two arms 27 and 2B of the fork receiving between themthe flattened upper end 29 of pin 24, the upper end 30 of a vertical link 30, and the right- 4 ward end of a horizontal link 3|. Pins 32, 33 and 34 establish pivotal connections between the two arms of the handle fork on the one hand and the pin 24, link 30 and link 3|, respectively.

The upper end 23 of blade pin 23 is forked to receive the leftward end of horizontal link 3|, and is pivotally connected thereto by a pin 43. The lower end of the vertical link 36 depending from the handle I 3, and the lower end of a second similar vertical link 35 are seated in slotted recesses 36 and 3! in the upper portion of the leg H, and are pivotally connected to the leg I! by pins 38 and 39, respectively, which span these recesses. The upper end 35 of the link 35 is forked, the branches of the fork embracing the link 3|, which is pivotally connected thereto by a pin Ail.

Grips 4| and 42 formed on the rightward ends of the handles I3 and M respectively enable the operator to grasp the handles between the thumb and fingers .of one hand and urges the handles toward each other with a squeezing pressure. As the handle i moves downwardly, it rocks on pivot pin 33, moving the blade pinid and rightward end of the blade |2 straight downwardly. Assuming that the lower blade is: and its handle i3 are stationary, and the blade holding pins 23 and 2c are in a vertical position, for clarity of description of the relative movement of the parts of the shears, then, as the handle |4 descends, the blade pin 24 will move vertically downward, and with it the pivot pin 32 at its upper end.

It is then apparent that the pivot pin 33 will have a slight arcuate movement about pivot pin as a center and toward the pivot pin 32, and the pivot pin 34 will move upwardly a distance about equal to the downward movement of blade holding pin 24, but will also be pulled a slight distance to the right of its initial position. The leftward end of link ill will be similarly rocked on pivot pin it which will move arcuately a slight distance toward pivot pin 47 as this pin 41 forces the blade pin 23 and the leftward end of blade i2 vertically downward a distance equal to the vertical downward movement of blade pin E i and the rightward end of blade l2. The pin bearing opening 4 in the rightward end of link 3| is in the form of a slot, being elongated horizontally to permit the handle I l and the link 3| to move apart sufiiciently to accommodate the arcuate movements of the pins 33 and 40 to and from each other as the tool is operated. The vertical width of this slot is such that the pivot pin 36 snugly fits between its top and bottom walls.

A biasing spring 45 is seated operatively between the end 29 of blade pin 24 and the yoke leg H to hold the handles I3 and Hi, and blades :2 and it normally in open position as determined by a stop it between blade l2 and yoke legs i1.

The essential condition of the disposition of the linkage connecting the handle M to the blade pins 23 and 2 3 is that the links 30 and 35, their pivoting axes at each end, and the pivoting axes of the pins 32, 34 and 3| be symmetrically related to an imaginary plane parallel to the blade pins 23 and 2d and in which lies the axis of pivot pin 34.

In the operation of the shears, the tool is placed on one edge of the work sheet with the sheet in position between the blades |2 and IS. The handles |3 and M are manually operated to cause the cutting blades to make successive cuts, the two portions of the severed Work sheet diverging vertically at a slight angle at 2|, with a minimum of bending of the metal. The manual pressure exerted is constant throughout the length of the cut made in each successive position of the tool on the work sheet. The tool can therefore be designed to use a practical maximum manual pressure during the entire cutting operation. The inherent limitations of the conventional shears require that it be designed to use a cutting pressure substantially less than the practical maximum manual pressure, since this maximum pressure must be reserved for use at those short portions of the travel of the point of severance which require a greater than average pressure.

This invention adapts the principle and advantages of the relatively rectilinearly moving cutting blades of square shears to manual handle-operated shears, to provide a use at maximum efficiency of manual pressure.

I claifii:

1. In a sheet metal cutter, the combination of: a horizontally disposed forwardly opening yoke shaped first member, having a first handle extending rearwardly therefrom with a manual grip at the rear end, the said first member having an upper leg and a lower leg, said lower leg having an elongated cutting edge; a second member having an elongated cutting edge; a first link pivotally connected to the upper leg and extending upwardly therefrom; a rearwardly extending first lever medianly fulcrumed to the outer end of the first link and having a manual grip at its rear end and formed with a longitudinally extending slot at its front end; a second link of the same effective length as the first link and pivotally connected to the upper leg in front of said first link and extending outwardly from the upper leg; a second lever medianly fulcrumed to the outer end of the second link and formed with an opening at its rear end cooperatively related to said slot to receive a hinge pin; a hinge pin seated in said slot and opening; and a pair of upwardly directed parallel rigid extensions of said second member slidably engaging said upper leg, the rearward of said extensions being pivotally connected to said first lever to the rear of said first link and the forward of said extensions being pivotally connected to the second lever in front of said second link, said links, extensions and pivotal connections of said links and extensions being symmetrically related to a plane parallel to the said extensions and embracing the axis of the hinge pin connection between said levers, and the extensions, links, levers and legs being dimensioned and related to dispose the cutting edges for shearing engagement at a small forwardly opening acute angle.

2. In a sheet metal cutter, the combination of: a first member having an elongated cutting edge; a second member having a second elongated cutting edge; a first straight pin rigidly secured to said second member adjacent one end 0f the cutting edge thereof; a second straight pin rigidly secured to said second member adjacent the other end thereof and arallel to said first pin; said second member being provided with two straight line parallel guideways for engaging said pins respectively, said pins and guideways being disposed to position one cutting edge at a slight acute angle to the other cutting edge and to constrain relative movement of the two members in a direction transverse to a work sheet in shearing position between said cutting edges; a lever pivoted to the outer end of one of said pins on a first axis; a lever extension pivoted at one end to the inner end of said lever on a second axis and at the other end to the outer end of the other pin on a third axis; a first link pivoted at its outer end to said lever on a fourth axis between said first and second axes and at its inner end to said first member on a fifth axis; a second link pivoted at its outer end to said lever extension on a sixth axis between said second and third axes and at its inner end to said, first member on a seventh axis, said seven axes, and said first and second links being symmetrically related to a plane passing through said second axis and parallel to said pins, and the lever and lever extension being formed at their pivotal connection to permit relative longitudinal movement; and means for applying a thrust to the outer end of the lever toward the plane of the work sheet.

3. In a sheet metal cutter, the combination of a yoke having an upper leg and a lower leg; at first handle on the yoke; an upwardly directed first cutting blade on the lower leg; a downwardly directed second cutting blade; a first holder mounted on the upper leg and rigidly connected to the end of the second blade to dispose the cutting edge of the second blade in cutting relation with the cutting edge of the first blade at a small forwardly opening acute angle thereto; a second holder rigidly connected to the front end of the second blade and slidably mounted on the upper leg for movement parallel to the movement of the first holder; a second handle pivotally connected to the outer end of the first holder to dispose the outer end of the handle in position for manual gripping relation with the first handle; and linkage connecting the forward end of the secondhandle to the upper leg and to the upper end of the second holder dimensioned and related to convert movement of the second handle toward the first handle into movements of the same-magnitude of the two holders respectively.

CLAUDE B. GARLAND.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,890,234 Pickering Dec. 6, 1932 2,069,685 Serdich Feb. 2, 1937 

